Widget in QWidgetAction disappears on second opening on macOS

If I put a widget like QPushButton via QWidgetAction into the context menu of a menu bar icon on macOS, the button will be shown on the first time I open the menu, but next time it will be invisible until I manually click on it. Obviously if I open the menu again, the button will be hidden as before.

I have tested this on almost all Qt version from 5.7.1 and all of them seem to be affected.

The OS was macOS 10.13.

Steps to reproduce:

• Download and compile the attached test application
• Run the application, a green Qt logo will appear on the menu bar
• Click on the small Qt logo on the menu bar, the context menu will appear with the button in it
• Close the context menu by clicking somewhere else
• Open the context menu again by clicking on the menu bar icon

Expected: the button is visible

Actual: the button is invisible and shows only when you click on it